Quasi-planter size for clematis - A few questions

pbl_ge(5/6)July 4, 2014

Please ignore the misleading subject line. I posted this elsewhere, and I think I'm being confusing. I'm going to try to rewrite this so that it's clearer.

We are installing a deck on the back wall of our garage, and we intend to leave square(ish) gaps (cut-outs) in the decking so that we can plant clematis to grow along the wall of the deck. (I've asked other questions about this here--yes the project is moving slowly!) It will be a mix of Huldine and something else, perhaps Jackmanii since it's so reliable.

Here's a drawing of the deck from above, that shows where the cut-outs will be along the wall of the garage:

Here's a picture of cut-outs, in case it's not clear what I mean:
Just imagine that those gaps are along a wall (back of the garage) and that clematis are planted in them, instead of trees.

I have a question and a problem.

The question is how big the cut-outs need to be for the clematis to grow through. When I look at the bases of the clematis that I have growing around the yard, they don't take up a lot of space. The plan above allows for 10" x 9" holes, which seem like they should be plenty big, but I'm not sure. What do you think? Another possible solution is to have those borders in the pic lift out, so that if we needed we could have bigger holes to tend to the plants.

The problem is that the surface of the deck will be 10" off the ground. I'm assuming we don't want to put the poor clematis plants down that far. So what do we need to do to help them reach the surface. The idea I've had to is to buy plastic planters (like ), cut the bottoms out, and put them in the ground, OR to build wooden boxes. Both of those ideas would bring the ground, and the bases of the clematis, up to the surface of the deck.

I am, however, worried about frost heave and hardiness. We're in upstate NY, where it gets plenty cold.

I hope this is clear. I'm spending a lot of time trying to explain this on another forum.

That's going to be beautiful, as is the first one you posted. I don't know how much room the need at the base but maybe someone will chime in about that. I could see mold/fungus being as issue as well as trying to clean the leaves/debris out since you said it will be off the ground a ways. I planted Morning Glories in a small area that will eventually be home to my clematis but it is shaded all but two hours about mid day until the vine can grow up past the stairs that shade it -then it gets morning sun until noon then very late afternoon sun. The vine struggled until it grew tall enough and now it's going nuts. If I put the clematis there I will wait until it's taller. Maybe you could do the same thing and just plant larger/taller vibes so they won't miss the sun?